The present invention relates to a gas supply apparatus, and particularly, to a gas supply apparatus suitable for supplying gas such as process gas to a reaction chamber for forming an insulating film on a semiconductor wafer.
In a process of manufacturing a memory such as DRAM of a semiconductor and a CPU such as a microcomputer, an interlayer insulating film such as silicon dioxide (SiO.sub.2) is used in forming an insulating film on a semiconductor wafer. As a film forming apparatus for forming the interlayer insulating film on the semiconductor wafer, a plasma CVD (Chemical Vapor Deposition) apparatus is used. The plasma CVD apparatus is provided with a reaction chamber for receiving process gas to form an interlayer insulating film on a semiconductor wafer, into which reaction chamber are supplied silane (SiH.sub.4), argon (Ar), oxygen (O.sub.2) or the like as process gas. In the maintenance, nitrogen (N.sub.2) as gas for purge or gas dilution is supplied to the reaction chamber, and in the cleaning, gas such as nitrogen trifluoride (NF.sub.3) is supplied thereto. As disclosed in Japanese Patent Laid-open No. Hei 6-284061, the gas supply apparatus for supplying these gases to the reaction chamber proposed so far employs a module mounting construction in which groups of blocks constituting one element of a gas supply flow path are dispersed and arranged on the base, a flow control valve (MFC: Mass Flow Controller) or an operating valve is arranged between the blocks, and opposite ends of the MFC or the operating valve are locked to the blocks by means of bolts to shorten the overall length of the gas supply apparatus.
When the module mounting construction for locking the MFC or the operating valve on the blocks is employed in place of connecting the MFC or the operating valve by means of pipes, the overall length of the gas supply apparatus can be shortened, and the MFC or the operating valve can be locked to the blocks by means of bolts from an upper portion, thus facilitating the maintenance of MFC.
However, the prior art has a construction in which a cable for supplying power and a signal to the MFC is connected from the upper portion of the MFC. It is necessary to have room for the cable in consideration of an allowable radius of curvature of the cable. This sometimes results in that the cable is projected upward of the MFC, the height of the whole MFC increases, and the space in height is restricted. Further, since the cable is installed in the air, it is sometimes in the way when the MFC is removed unless processing of the cable is taken into consideration. Moreover, since a cable is long, the MFC is sometimes erroneously operated due to noises.
It is an object of the present invention to provide a gas supply apparatus capable of making use of a region between elements constituting a gas supply flow path for a region for a signal transmission system to reduce an occupying space.